Black mold growing on my clay tile roof

I live in the Philippines, so it's pretty much hot and humid here all year round. And we have really had lots of rain here for the last 6 months.

About 1 year ago, we had a new house built and had a ceramic clay tile roof installed. The tiles were imported from Spain.

After 1 year now, I have noticed alot of a black colored mold on the tiles. By wife's brother and another relative have now been on the roof for 3 full days scrubbing the tiles with tide soap and bleach. It looks like they will need at least another 1 or 2 days of hand scrubbing. This is removing all the black discoloration, but it certainly is labor intensive.

I was just wondering if anyone here has seen a problem like this with a clay tile roof in hot and wet areas in the US such as maybe Florida or the Houston area?

Had I known that these roof tiles are supseptable to black mold formation, I certainly would not have installed them.

Here is a photo of the roof (might be a little hard to see the black discoloration in certain areas) do to the various color shades of each roof tile ... but it's certainly discolored in certain areas.